Exhaust Manifold Gasket

ABSTRACT

An exhaust manifold gasket assembly having at least two layers and a series of tabs and recesses. The gasket has a first outer layer with an outer surface, an inner surface, two bolt hole flanges, a central aperture, and internal square cut-outs. The surfaces are bounded by an outer perimeter portion, with foldable tabs. A first inner layer and a second inner layer each with an outer surface, an inner surface, two bolt hole flanges, a central aperture, and pairs of internal slits. The surfaces are surfaces bounded by an outer perimeter portion, with locator tabs. Each inner layer has a bead circumferentially around the central aperture. A second outer layer may be provided having an outer surface, an inner surface, two bolt hole flanges, a central aperture, and internal square cut-outs. The surfaces are bounded by an outer perimeter portion, with recesses.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application filed off of U.S.patent application Ser. No. 61/458,852 filed on Dec. 2, 2010, which isincorporated by reference in its entirety herein. This non-provisionalapplication is being filed during the pendency of U.S. patentapplication Ser. No. 61/458,852.

FIELD OF THE INVENTION

The present invention relates to an exhaust manifold gasket for use ininternal combustion engines.

BACKGROUND OF THE INVENTION

Gaskets essentially are used to seal and prevent leakage between twoparts. Exhaust manifold gaskets for internal combustion engines seal anygaps and prevent leakage when the mating surfaces of the cylinder headand the exhaust manifold are bolted together. The gaskets may be made oflayers and one or more of the layers may include a bead. Sealing thejoined area between the parts can be difficult because the cylinderhead, manifold and gasket all move due to pressure and temperaturefluctuations. There are also problems due to thermal expansion andthermal contraction, which occurs when the temperature varies in thecylinder head and the manifold.

Thermal motion, resulting from hot exhaust gases, increasing combustionpressure, steep thermal swings, and sheer stresses are created in thejoined area between the cylinder head and the exhaust manifoldincreasing the risk of horizontal motion and shifting of the gasketlayers, such as in a multi-layer steel (MLS) gasket. When this occurs,the layers shift and the mechanical beads in the gasket layers canbecome misaligned. This reduces the sharing capabilities of the beadslocated on the various layers, and the misaligned beads may induceunusual stress concentrations.

There are also multiple openings in the cylinder head and the manifoldfor exhaust gases and bolts holes. The areas around these openings areknown to be put under additional stresses and leakage is common due tomovement and misalignment of the gasket layers.

Traditionally, the various gasket layers are aligned and held in placeduring gasket assembly by welding, eyeleting or form-locking. Theeyeleting and form-locking methods both add thickness to the gasket andtherefore must be located outside of the joined area, which is notideal. While welding does not necessarily add thickness to the gasket,the weld spots may crack and/or break due to horizontal hardware motionwhich allows the gasket layers to shift.

In view of the foregoing disadvantages of the prior art, it would beadvantageous for a MLS gasket to be able to prevent or resist horizontalmotion and misalignment of the layers to the extent that it negativelyaffects performance of the gasket.

SUMMARY OF THE INVENTION

The present invention is directed toward an exhaust manifold gasketassembly having at least two or more layers, and utilizing a series oftabs, recesses, square cut-outs and pairs of slits to maintain alignmentof the layers. The exhaust manifold gasket assembly has a first outerlayer comprising an outer surface, an inner surface, two bolt holeflanges with bolt holes therethrough, a central aperture between theflanges, and at least two internal square cut-outs. The surfaces arebounded by an outer perimeter portion, wherein at least two foldabletabs extend from the outer perimeter portion. A first inner layer and asecond inner layer each comprise an outer surface, an inner surface, twobolt hole flanges with bolt holes therethrough, a central aperturebetween the flanges, and at least two pair of internal slits. Thesurfaces are bounded by an outer perimeter portion, wherein at least onelocator tab is located. Each of the inner layers also has a beadcircumferentially extending about the central aperture inboard the outerperimeter portion of each of the inner layers. A second outer layer maybe provided and comprises an outer surface, an inner surface, two bolthole flanges with bolt holes therethrough, a central aperture betweenthe flanges, and at least two internal square cut-outs. The surfaces arebounded by an outer perimeter portion, wherein at least two recesses arelocated.

In accordance with the present invention, it has been discovered thatonce the layers are assembled together, horizontal movement between thelayers is significantly decreased, and the beads located on the innerlayers remain aligned reducing unusual stress concentrations.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as other advantages of the present invention, willbecome readily apparent to those skilled in the art from the followingdetailed description when considered in the light of the accompanyingdrawings in which:

FIG. 1 is a partial perspective exploded view of the present inventionwith an exhaust manifold gasket, an exhaust manifold and cylinder head;

FIG. 2 is a top view of the assembled exhaust manifold gasket in FIG. 1;

FIG. 3 is a cross-sectional view of a portion of the embodiment of FIG.2 along line 3-3;

FIG. 4 is a cross-sectional view of a portion of the embodiment of FIG.2 along line 4-4;

FIG. 5 is a cross-sectional view of a portion of the embodiment of FIG.2 along line 5-5;

FIG. 6 is a perspective assembled view of the embodiment of FIG. 2;

FIG. 7 is a perspective exploded view of the layers of the embodiment ofFIG. 2;

FIG. 8 is a top view of a layer of the embodiment of FIG. 2;

FIG. 9 is a top view of a layer of the embodiment of FIG. 2;

FIG. 10 is a top view of a layer of the embodiment of FIG. 2;

FIG. 11 is a top view of a layer of the embodiment of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is to be understood that the invention may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the specific devices andprocesses illustrated in the attached drawings, and described in thefollowing specification are simply exemplary embodiments of theinventive concepts defined in the appended claims. Hence, specificdimensions, directions or other physical characteristics relating to theembodiments disclosed are not to be considered as limiting, unless theclaims expressly state otherwise.

As shown in FIG. 1, an exhaust manifold gasket assembly 10 is positionedbetween a cylinder head 12 and an exhaust manifold 14, so as to createan air tight seal between the two parts when they are bolted together.Both the cylinder head 12 and the exhaust manifold 14 are parts of aninternal combustion engine (not shown.) The cylinder head 12 sits on topof a cylinder block (not shown.) It closes in the top of the cylinder,to form a combustion chamber. The exhaust manifold 14 collects exhaustgases from the cylinder combustion chamber, and delivers the gases to anexhaust pipe. Both the cylinder head 12 and the exhaust manifold 14 havebolt apertures 12 a, 12 b, 14 a, 14 b which align with each other, andeach has a flat surface 16, 18 for receiving an exhaust manifold gasketassembly between them, as shown in the figure.

Exhaust manifold gasket assemblies are manufactured in accordance withthe various shapes of cylinder heads and exhaust manifolds, and includenumerous openings, such as exhaust gasket openings and bolt holes. FIG.1 depicts one embodiment of an exhaust manifold gasket assembly 10;however, other shapes, sizes and designs are permissible. Varioussealing means are provided in the gasket assembly for sealing around therespective openings.

The embodiment of the exhaust manifold gasket assembly 10, as depictedin FIGS. 2-11, comprises a first outer layer 20, a second outer layer118, a first inner layer 54 and a second inner layer 86. It is alsowithin the scope of the invention for there to be more or fewer layers.The two outer layers 20, 118 and the two inner layers 54, 86 may each bemade of a metallic material, such as steel.

As shown in FIGS. 6, 7 and 8, the first outer layer 20 comprises anouter surface 22, an inner surface 24, two bolt hole flanges 26, 28 withbolt holes 30, 32 therethrough, a central aperture 34 between theflanges 26, 28, and at least two internal square cut-outs. While asdepicted in the figures four internal square cut-outs 36, 38, 40, 42 areshown, it is also within the scope of the invention for there to be moreor fewer internal square cut-outs.

The surfaces 22, 24 of the first outer layer 20 are bounded by an outerperimeter portion 44, wherein foldable tabs 46, 48, 50, 52 are formedfrom the outer perimeter portion 44. The foldable tabs 46, 48, 50, 52extend unitarily outward from the outer perimeter portion 44. While asdepicted in FIGS. 7 and 8 four foldable tabs 46, 48, 50, 52 are shown,it is also within the scope of the invention for there to be more orfewer tabs. The foldable tabs 46, 48, 50, 52 and internal squarecut-outs 36, 38, 40, 42 are generally located toward the narrow ends ofthe oval outer perimeter portion 44 between the bolt hole flanges 26, 28and the central aperture 34.

The internal square cut-outs 36, 38, 40, 42 are oriented parallel withand adjacent the outer perimeter portion 44. The internal squarecut-outs 36, 38, 40, 42 insure that there are only four layersoverlapping at any one point. This feature ensures that when the gasketis installed, the total gasket thickness is never greater than theoriginal number of layers in the gasket assembly, as depicted in FIG. 4.The foldable tabs 46, 48, 50, 52 are located outboard of the internalsquare cut-outs 36, 38, 40, 42 and are slightly narrower in width thanthe internal square cut-outs 36, 38, 40, 42. The foldable tabs 46, 48,50, 52 also have a length longer than the thickness of the first outerlayer 20.

As depicted in FIGS. 7, 9 and 10, the first inner layer 54 and thesecond inner layer 86 each comprise an outer surface 56, 88, an innersurface 58, 90, two bolt hole flanges 60, 62, 92, 94 with bolt holes 64,66, 96, 98 therethrough, a central aperture 68, 100 between the flanges60, 62, 92, 94, and at least two pair of internal slits 70, 72, 74, 76,102, 104, 106, 108.

The surfaces 56, 58, 88, 90 of each of the inner layers 54, 86 arebounded by an outer perimeter portion 78, 110. The outer perimeterportion 78, 110 is generally oval in shape and includes locator tabs 80,82, 112, 114. As shown in FIGS. 9 and 10, the locator tabs 80, 82, 112,114 extend unitarily outward from the outer perimeter portion 78, 110.Locator tabs 80, 82, 112, 114 are generally utilized during assembly ofthe gasket between two parts to ensure that it is in the correctposition to obtain optimum sealing capabilities. While as depicted inthe figures two locator tabs 80, 82, 112, 114 are shown on each of theinner layers 54, 86, it is also within the scope of the invention forthere to be more or fewer locator tabs. As depicted in the figures, thelocator tabs 80, 82, 112, 114 on each of the inner layers 54, 86 arelocated on opposite sides, diagonally across from each other. Thelocator tabs 80, 82, 112, 114 are generally located toward the narrowends of the oval outer perimeter portion 78, 110 between the bolt holeflanges 60, 62, 92, 94 and central aperture 68, 100.

As shown in FIGS. 4 and 7, the pairs of internal slits 70, 72, 74, 76,102, 104, 106, 108 on each of the first and second inner layers 54, 86are aligned with one another. The pairs of internal slits 70, 72, 74,76, 102, 104, 106, 108 are located parallel to and internally inboard ofthe outer perimeter portion 78, 110, and generally located toward thenarrow ends of the oval outer perimeter portion 78, 110 between the bolthole flanges 60, 62, 92, 94 and central aperture 68, 100. The individualslits in each pair 70, 72, 74, 76, 102, 104, 106, 108 are the same andparallel one another. One slit in each pair 70, 72, 74, 76, 102, 104,106, 108 is adjacent the outer perimeter portion 78, 110. The two innerlayers 54, 86 are a mirror image of one another, shown in FIGS. 9 and10.

The first inner layer 54 and the second inner layer 86 each alsocomprise a bead 84, 116 which circumferentially extends about thecentral aperture 68, 100 and is inboard of the outer perimeter portion78, 110, as depicted in FIGS. 2 and 3.

As depicted in FIGS. 7 and 11, the second outer layer 118 comprises anouter surface 120, an inner surface 122, two bolt hole flanges 124, 126with bolt holes 128, 130 therethrough, a central aperture 132 betweenthe flanges 124, 126, and at least two internal square cut-outs. Whileas depicted in the figures four internal square cut-outs 134, 136, 138,140 are shown, it is also within the scope of the invention for there tobe more or fewer internal square cut-outs.

The surfaces 120, 122 of the second outer layer 118 are bounded by anouter perimeter portion 142. The outer perimeter portion 142 isgenerally oval in shape and includes recesses 144, 146, 148, 150. Asdepicted in the figures, the recesses 144, 146, 148, 150 extend inwardfrom the outer perimeter portion 142. While as depicted in the figuresfour recesses 144, 146, 148, 150 are shown, it is also within the scopeof the invention for there to be more or fewer recesses.

The recesses 144, 146, 148, 150 and internal square cut-outs 134, 136,138, 140, as depicted in FIGS. 7 and 11, are generally located towardthe narrow ends of the oval outer perimeter portion 142 between the bolthold flanges 124, 126 and the central aperture 132. The internal squarecut-outs 134, 136, 138, 140 are oriented parallel with and adjacent theouter perimeter portion 142. The internal square cut-outs 134, 136, 138,140 insure that there are only four layers overlapping at any one point.This feature ensures that when the gasket is installed, the total gasketthickness is never greater than the original number of layers in thegasket assembly, as depicted in FIG. 4. The recesses 144, 146, 148, 150are parallel with and located outboard of the internal square cut-outs134, 136, 138, 140 and are substantially the same width as the internalsquare cut-outs 134, 136, 138, 140.

As shown in FIGS. 3 and 5, the inner surfaces 24, 122 and the outersurfaces 22, 120 of each of the outer layers 20, 118 are planar andparallel to one another, and define between them a substantiallyconstant thickness.

As shown in FIGS. 6 and 7, the central aperture 34, 68, 100, 132 in allthe layers 20, 54, 86, 118 are aligned with one another and have acomplimentary shape when the layers 20, 54, 86, 118 are placed togetherfor assembly. When all the layers 20, 54, 86, 118 are aligned, the beads84, 116 of each of the inner layers 54, 86 are also radially alignedwith one another. Once the layers 20, 54, 86, 118 are placed togetherthey may be welded to hold them together, although with this embodimentwelding is not necessary.

It can be appreciated from FIGS. 2, 6 and 7 that the foldable tabs 46,48, 50, 52, internal square cut-outs 36, 38, 40, 42, 134, 136, 138, 140and recesses 144, 146, 148, 150 of the outer layers 20, 118 are inalignment with one another, and the pairs of internal slits 70, 72, 74,76, 102, 104, 106, 108 of the inner layers 54, 86 are in alignment withone another. For example, the foldable tabs 46, 48, 50, 52 on the firstouter layer 20 align with and engage the recesses 144, 146, 148, 150 onthe second outer layer 118.

As can also be appreciated from FIGS. 5, 6 and 7 when the layers 20, 54,86, 118 are assembled, the inner surface 58 of the first inner layer 54is directly adjacent the inner surface 24 of the first outer layer 20,and the outer surface 88 of the second inner layer 86 is directlyadjacent the inner surface 122 of the second outer layer 118. The outersurface 56 of the first inner layer 54 is directly adjacent the innersurface 90 of the second inner layer 86 when assembled.

Ultimately when the layers 20, 54, 86, 118 are assembled, as depicted inFIGS. 4 and 6, the foldable tabs 46, 48, 50, 52 on the first outer layer20 are folded into a C-shape which encloses around the outer perimeterportion 78, 110, 142 of each of the first inner layer 54, second innerlayer 86 and the second outer layer 118. The internal square cut-outs36, 38, 40, 42, 134, 136, 138, 140 on each of the outer layers 20, 118insure that there are only four layers overlapping at any one point.This feature ensures that when the gasket is installed, the total gasketthickness is never greater than the original number of layers in thegasket assembly, as depicted in FIG. 4. This configuration ensures thatthe layers remain in alignment and in direct contact with each other.

The use of the series of foldable tabs, recesses, and square cut-outsand pairs of slits in the various gasket layers that align during layerassembly eliminates the ability of the layers to slide indecently if thewelds or other means of attachment that may have been used fails. Thefoldable tabs act as limiters to the horizontal movement of the layerswithin the joint. This combination of tabs and recesses does not addadditional thickness to the gasket in the region between the joint. Theability to locate these features within the joint eliminates thehorizontal motion from “unfolding” the tabs that are acting as themotion limiters.

1. An exhaust manifold gasket, comprising: a first outer layercomprising an outer surface, an inner surface, two bolt hole flangeswith bolt holes therethrough, a central aperture between said flanges,and at least two internal square cut-outs, said surfaces bounded by anouter perimeter portion, wherein at least two foldable tabs extend fromsaid outer perimeter portion; a first inner layer and a second innerlayer each comprising an outer surface, an inner surface, two bolt holeflanges with bolt holes therethrough, a central aperture between saidflanges, and at least two pair of internal slits, said surfaces boundedby an outer perimeter portion, wherein at least two locator tabs extendfrom said outer perimeter portion of each of said first inner layer andsaid second inner layer, and a bead circumferentially extending aboutsaid central aperture inboard said outer perimeter portion of said firstinner layer and said second inner layer; and a second outer layercomprising an outer surface, an inner surface, two bolt hole flangeswith bolt holes therethrough, a central aperture between said flanges,and at least two internal square cut-outs, said surfaces bounded by anouter perimeter portion, wherein at least two recesses extend inwardfrom said outer perimeter portion outboard of each of said internalsquare cut-outs.
 2. An exhaust manifold gasket according to claim 1,wherein said foldable tabs on said first outer layer are aligned withsaid recesses on said second outer layer.
 3. An exhaust manifold gasketaccording to claim 1, wherein said pairs of internal slits on each ofsaid first inner layer and said second inner layer are aligned with oneanother.
 4. An exhaust manifold gasket according to claim 1, whereinsaid locator tabs on each of said first inner layer and said secondinner layer are opposite and diagonal from each other.
 5. An exhaustmanifold gasket according to claim 1, wherein said internal squarecut-outs on each of said first outer layer and said second outer layerare aligned with one another.
 6. An exhaust manifold gasket according toclaim 1, wherein said central apertures of all said layer are alignedwith one another and have a complimentary shape to one another.
 7. Anexhaust manifold gasket according to claim 1, wherein said beads of saidinner layers are radially aligned with one another.
 8. An exhaustmanifold gasket according to claim 1, wherein said inner and outersurfaces on each of said outer layers are planar and parallel and definebetween them a substantially constant thickness.
 9. An exhaust manifoldgasket according to claim 1, wherein four foldable tabs extend from saidouter perimeter portion of said first outer layer.
 10. An exhaustmanifold gasket according to claim 1, wherein two locator tabs extendfrom said outer perimeter portion of each of said first inner layer andsaid second inner layer.
 11. An exhaust manifold gasket according toclaim 1, wherein said inner surface of said first inner layer isdirectly adjacent said inner surface of said first outer layer.
 12. Anexhaust manifold gasket according to claim 1, wherein said outer surfaceof said second inner layer is directly adjacent said inner surface ofsaid second outer layer.
 13. An exhaust manifold gasket according toclaim 1, wherein said outer surface of said first inner layer isdirectly adjacent said inner surface of said second inner layer.
 14. Anexhaust manifold gasket according to claim 1, wherein said foldable tabson said first outer layer are folded into a C-shape and enclose aroundsaid outer perimeter portion of each of said first inner layer, saidsecond inner layer and said second outer layer.
 15. An exhaust manifoldgasket, comprising: a first layer comprising an outer surface, an innersurface, two bolt hole flanges with bolt holes therethrough, a centralaperture between said flanges, and at least two internal squarecut-outs, said surfaces bounded by an outer perimeter portion, whereinat least two foldable tabs extend from said outer perimeter portion; anda second layer comprising an outer surface, an inner surface, two bolthole flanges with bolt holes therethrough, a central aperture betweensaid flanges, and at least two pair of internal slits, said surfacesbounded by an outer perimeter portion, wherein two locator tabs extendfrom said outer perimeter portion, and a bead circumferentiallyextending about said central aperture inboard said outer perimeterportion.
 16. An exhaust manifold gasket according to claim 15, whereinsaid internal square cut-outs on said first layer are aligned with saidpairs of internal slits on said second layer.
 17. An exhaust manifoldgasket according to claim 15, wherein said locator tabs on said secondlayer are opposite and diagonal from each other.
 18. An exhaust manifoldgasket according to claim 15, wherein said central apertures of saidboth layers are aligned with one another and have a complimentary shapeto one another.
 19. An exhaust manifold gasket according to claim 15,wherein four foldable tabs extend from said outer perimeter portion ofsaid first layer.
 20. An exhaust manifold gasket according to claim 15,wherein said foldable tabs on said first outer layer are folded into aC-shape and enclose around said outer perimeter portion of said secondlayer.